Sewing machine throat plates



Ma'y 12, 1959 J. A. LOMBARDO SEWING MACHINE THROAT PLATES Filed May 22, 1957 Figrl'.

.w .9 M U 2 F mm N w R a w 3 J L Y Ir I B United States Patent SEWING MACHINE THROAT PLATES Joseph A. Lombardo, Sn-afford, Conm, assignor to The Singer Manufacturing Company, Elizabeth, N.J., a corporation of New Jersey Application May 22, 1957, Serial No. 660,901

6 Claims. (Cl. 112-260) This invention relates to a throat plate for a sewing machine and, more particularly, to a throat plate for a sewing machine having a free-ended work-supporting bed of the type adapted to accommodate tubular articles.

Free-ended work-supporting beds are commonly termed cylinder beds in the sewing machine art whether or not the bed is of a true cylindrical shape.

Cylinder bed sewing machines known in the prior art are fitted with either one of two general types of workfeeding mechanisms, i.e., either a feed-across-the-arrn type which advances a work fabric in a direction transversely of the longitudinal axis of the cylinder bed or a feed-up or feed-off-the-arm type which advances a work "ice Carried within the cylinder bed is a loop taker (not shown) which may be of any conventional type and cooperates in the formation of stitches with an endwise re- J this invention applied thereto. with a needle aperture 19 and with slots 20 "to accommothe endwise reciprocatory needle.

means of a set screw 26.

ciprocatory needle 15 carried by the sewing head. The bed is also provided with a work-feeding mechanism including a serrated work-engaging feed dog 16 which is opposed by a presser foot 17 carried by the sewing head and preferably spring biased toward the feed dog. The longitudinal axis of the cylinder bed 11 is indicated by the line x-x in Fig.4. The feed mechanism is preferably of a type which will actuate the feed dog so as to advance a work fabric in a direction transversely of the longitudinal axis of the cylinder bed and thus feed the work across the cylinder bed. In Fig. 4 the customary forward direction of the feed is indicated by an arrow.

Fig. 2 is a perspective view of a throat plate 18 having The throat plate is formed date the feed dog 16. Means are also provided for securing the throat plate on the free end of the cylinder bed with the needle aperture 19 disposed in registry with For this purpose, a screw 21 is threaded into the throat plate with the head of the screw projecting outwardly from beneath the throat plate so as to engage beneath a top cover plate 22 of the cylinder bed to hold the throat plate in place. A guide pin 23 carried by the cylinder bed enters a guide slot 24 in the throat plate so as to locate the throat plate properly when the throat plate is being positioned on the machine. At the free or outboard extremity of the cylinder bed an upstanding latch pin 25 is secured in the bed by The latch pin is formed with an annular groove 27 which accommodates a spring wire latch finger 28 secured beneath the throat plate by a fastening screw 29. A stop screw 30 beneath the throat plate maintains the spring latch finger in position to engage the latch pin when the throat plate is being posi- It is also an object of this invention to provide a means i of the above character on a throat plate which may be removed quickly and easily from the sewing machine and replaced readily by a conventional throat plate.

With the above and additional objects and advantages in view as will hereinafter appear, this invention comprises the devices, combinations, and arrangements of parts hereinafter described and illustrated in the accompanying drawing in which:

Fig. 1 represents a front elevational view of a cylinder 1, 1

bed sewing machine with portions of the supporting base and bracket arm broken away and having this invention applied thereto,

Fig. 2 is a perspective view of a throat plate embodying this invention,

Fig. 3 represents a top plan view of the free end portion of the cylinder bed of Fig. 1 including a representation of a work fabric as it is formed into a tube and introduced to the stitch forming mechanism of the machine.

Fig. 4 represents a top plan view of the free end portion of the cylinder bed of Fig. 1 including a representation of a work fabric illustrating the manner in which the fabric is stitched into a tube and then directed up the cylinderbed with this invention.

Fig. 5 is a cross sectional view taken substantially along line 5-5 of Fig. 3, illustrating the latch device for holding the throat plate in place on the cylinder bed.

Referring to the drawing, Fig. 1 illustrates a sewing machine of the type having a free-ended cylinder bed 11 projecting from a supporting base of which a portion is shown at 12. Also carried by the supporting base is a conventional standard 13 sustaining a bracket arm (not shown) which terminates in a sewing head 14 overhanging the free end of the cylinder bed.

tioned on the cylinder bed, and an aperture 31 is formed in the throat plate to receive the top of the latch pin25. The throat plate may be removed readily from the machine by simplylifting the outboard extremity so as to disengage 1;; the latch and then sliding the plate toward the free end of the bed to move the head of the screw 21 from under the top cover plate 22.

The needle aperture 19 in the throat plate may be considered as the stitching point on the machine since the 1 rnation. The end and rear side edges of the throat plate are preferably formed, as illustrated in Figs. ,3 and 4, to coincide substantially with the outline of the cylinder bed. The tongue 32, however, projects beyond the outline of the projection of the cylinder bed normal to the throat plate and thus provides an extension of the work-supporting surface in front of the stitching point. The tongue extends laterally on both sides of the line of scam formation y-y. On the inboard side of the line of seam formation, the side edge 33 of the tongue is concave in plan configuration to define a work-controlling edge against which the folds of fabric at the inside corner of a fabric tube are confined as the tube is turned and directed up the cylinder bed.

Figs. 3 and 4 illustrate the manner in which a fabric 34 is formed into a tube and directed up the cylinder bed using this invention. Fig. 3 illustrates the arrangement of a stripof fabric 3.4 as the oppositeedges of the strip are over-lapped and the lapped edges are directed along the line of seam formation yfi to the stitching point. Note that even before the material reaches the stitching point the inboard side of the tube being formed will have engaged the cylinder bed and folds 35 will have begun to form in the fabric at this point. As the stitching progresses, the stitched tube is turned as illustrated in Fig. 4 and directed up the cylinder bed. The fabric tube is turned about the fabric folds 35 at the inside corner of the fabric .tube. The folds 35 are constrained on the inboard side of the line of seam formation by the workcontrolling edge 33 of the throat plate tongue and thereby prevented from shifting toward the free end of the cylinder bed and across the line of seam formation.

Since the folds are prevented from sliding laterally toward the line of seam formation, from which the folds would be drawn directly to the stitching point, there is little danger of the folds being stitched into the seam. With :this invention, a perfectly seamed tube may thus be stitched quickly and easily on a sewing machine not originally intended for forming a tube. Since the throat plate formed in accordance with this invention may be replaced in a moment by a conventional throat plate, the Sewing machine may be readied for either type of work in an instant.

Having thus described the nature of the invention, what I claim herein .is:

1. In a free-ended cylinder bed sewing machine having an endwise reciprocatory needle and a Work-feeding mechanism adapted to advance a work fabric tube in a direction transversely of the longitudinal axis of the cylinder bed thereby to define a line of seam formation across the cylinder bed, a throat plate comprising a substantially fiat plate formed with a needle aperture, means for securing said plate on said cylinder bed with said needle aperture in registry with the endwise reciprocatory needle, and means on the throat plate disposed in front of the needle aperture considered in the line of seam formation and extending free of the cylinder bed to define a Work-controlling shoulder against which the folds at the inside corner of said fabric tube are confined as the tube is turned and directed up the cylinder bed.

2. In a free-ended cylinder bed sewing machine having an endwise reciprocatory needle and a work-feeding mechanism adapted to advance a work fabric in a direction transversely of the longitudinal axis of the cylinder bed thereby to define a line of scam formation across the cylinder bed, a throat plate comprising a substantially flat plate formed with a needle aperture, means for securingsaid plate on said cylinder bed with said needle aperture in registry with the endwise reciprocatory needle, and means on the throat plate disposed in front of the needle aperture considered in the line of seam formation and extending beyond the outline of the projection normal to said flat throat plate of said cylinder bed.

3. In a free-ended cylinder bed sewing machine machine having an endwise reciprocatory needle and a work-feeding mechanism adapted to advance a work fabric in a directionv transversely of the longitudinal axis of the cylinder bed thereby todefine a line of seam formation across the cylinder bed, a throat plate comprising a substantially flat plate formed with a needle aperture, means for securing said plate on said cylinder bed with said needle aperture in registry with the endwise reciprocatory needle, and means on the throat plate disposed in front of the needle aperture considered in the line of seam formation and extending beyond the outline of the projection normal to said fiat throat plate of said cylinder bed, at least a portion of said means being disposed inboard of said line of stitch formation on the free-ended cylinder bed.

4. In a free-ended cylinder bed sewing machine having an endwise reciprocatory needle and a work-feeding mechanism adapted to advance a work fabric in a direction transversely of the longitudinal axis of the cylinder bed thereby to define a line of seam formation across the cylinder bed, a throat plate comprising a substantially flat plate formed with a needle aperture, means for securing said plate on said cylinder bed with said needle aperture in registry with the endwise reciprocatory needle, and .a tongue formed on the'side edge of said throat plate which is disposed in front of the needle aperture considered in the line of seam formation, said tongue extending beyond the outline of the projection normal to said fiat throat :plate of said cylinder bed.

5. In a free-ended cylinder bed sewing machine having anendwise reciprocatory needle and a work-feeding mechanism adapted to advance a work fabric in a direction transversely of the longitudinal axis of the cylinder bed thereby to define a line of seam formation across the cylinder bed, a throat plate comprising a substantially flat plate formed with a needle aperture, means for securing 1 said plate on said cylinder bed with said needle aperture J in registry with the endwise reciprocatory needle, and a tongue formed on the side edge of said throat plate which is disposed in front of the needle aperture considered in the line of scam formation, said tongue extending beyond the outline .of the projection normal to said flat throat plate of said cylinder bed, and having at least a portion thereof extending inboard of said line of stitch formation.

6. In a free-ended cylinder bed sewing machine having an endwise reciprocatory needle and a Work-feeding mechanism adapted to advance a Work fabric tube in a direction transversely of the longitudinal axis of the cylinder bed thereby to define a line of seam formation across the cylinder bed, a throat plate comprising a substantially fiat plate formed with a needle aperture, means for securing said plate on said cylinder bed with said needle aperture in registry with the endwise reciprocatory needle, a tongue formed on the side edge of said throat plate which is disposed in front of the needle aperture considered in the line of seam formation, said tongue extending beyond the outline of the projection normal to said flat throat plate of said cylinder bed, and a work controlling edge formed on said tongue inboardof said line of scam formation against which Work-controlling edge the folds at the inside corner of said fabric tube are confined as the tube is turned and directed up the cylinder bed.

422,558 Whitmore Mar. 4, 1890 Gould Feb. 17, 1914' 

